30J NATURAL HISTORY OF AQUATIC INSECTS CH. 



I saw in the evening a great crowd of small Flies, 

 a little larger than Gnats. So many settled on my 

 clothes that I was completely covered with them, 

 and great numbers left their thin pellicles behind on 

 my clothes. I observed that they betook themselves 

 to the water, and sported there like Palingenia. The 

 larvae of this second species do not live in mud, or 

 make tubes, but live for the most part on stony or 

 sandy bottoms. They are tougher and hardier than 

 Palingenia, and their skin is more like that of a Crab 

 or a Shrimp. They have gills along the sides of the 

 body. If any one in the month of June takes stones 

 out of the Rhine, the Leek, or other of our native 

 streams, he will see many of the larvae clinging to 

 them. I have seen the same thing in the Loire, the 

 Seine, and other rivers of France." 



Reaumur gives us a very lively account of one 

 species of Ephemera (Polymitarcys virgo), besides 

 notices of some others. The following is a condensed 

 translation of the twelfth memoir of his sixth 

 volume. 



" Many kinds of Flies are doomed to perish on the 

 very day on which they emerge, and are hence called 

 Ephemerae or Dayflies. Some do not even see the 

 light of the sun ; they emerge after he has set, and 

 die before he rises again ; others live an hour or even 

 half an hour only. 



" The wings of the adult Ephemera are trans- 

 parent, and shorter as well as broader than those 

 of common Flies. There are two pairs, 1 the fore 



1 Sometimes reduced to one, the hind pair being undeveloped 

 in certain species. 



